[Changes in the iron uptake of bone marrow cells in exercised rats].

The changes in transferrin(Tf)-bound and non-Tf-bound iron uptake were observed in bone marrow cells from rats with exercise-induced low iron status. Female rats were randomly divided into an exercise group (EG) and a sedentary group (SG). At the end of a 6-month period, the bone marrow cells were freshly isolated. The Tf receptor number on the surface of erythroblasts was 890150+/-164849 molecules/cell in SG and 2175360+/-462737 molecules/cell in EG (P<0.05). No significant difference in dissociation constant value was found between the two groups. The plateau of Tf internalization and the rates of cellular iron accumulation in EG were significantly higher than controls. Amounts of Tf-bound iron and Fe(II) uptake into cytosolic or stromal fractions were significantly higher in EG than those in cytosolic or stromal fractions of SG. With respect to the specific process of Fe(II), the michaelis constant value of iron uptake into the cytosol, rather than the stroma, in EG was significantly lower than that in SG; and the maximum rate of iron uptake into the stroma in EG was significantly higher than that in SG. The results show that exercise can increase Tf receptor-mediated and carrier-mediated iron uptake in bone marrow cells. The increased Tf-bound and Tf-free iron uptake may be helpful for heme synthesis.